Recently, there have been widely known, various plastics which have been modified with siloxane compounds.
For the purpose of modifying synthetic resins, polysiloxanes containing hydroxy terminal groups have already been used. In the GB patent No. 880,022, there is disclosed a method of reacting a polyoxyalkylene with a polysiloxane containing two alkoxy groups at ends, to give polyoxyalkylene-polysiloxanediol block copolymers.
Also, a process for preparing new polysiloxanes containing hydroxy terminal groups is proposed in U.S. Pat. No. 3,981,898, in which polysiloxanes containing hydroxy terminal groups are prepared by reacting polysiloxanes with polyols and diols.
However, when said polysiloxanes were used as modifying agents for thermosetting resins such as unsaturated polyesters, epoxy resins and the like, there was a disadvantage in that an excess flash which occurred during the molding process.
On the other hand, in the DE patent No. 1,618,836, there were used trisiloxanols, having hydroxy groups directly bonded to Si atoms, as the plastic modifier. However, such siloxanol compounds have a disadvantage in that it is difficult to process these compounds with organic resins and hence they cannot be suitably used as modifying agents for synthetic resins.
Therefore, the present inventors have eagerly studied to overcome the prior disadvantages as described above, and consequently have developed novel polysiloxanes containing imide terminal groups which are effectively used as modifying agents, especially for thermosetting resins such as unsaturated polyesters, epoxy resins, polyamides and so on.